On Tuesday, the Tennessee state senate passed legislation that extends murder and assault laws to cover the early stages of pregnancy: before six weeks, when the fetus is still technically considered an embryo. Supporters say the measure is to ensure that additional charges can be brought against someone who harms a pregnant woman.

Criminal charges are now being brought against women in Alabama for “chemical endangerment of a child” which has been utilized to penalize mothers who use drugs during their pregnancy and has a mandatory sentence of 10 years to life (if the baby dies). Since the 2006 enactment of the statute, 60 new mothers in the state have been prosecuted. But now, groups like Planned Parenthood, the A.C.L.U. and the American Congress of Obstetricians and Gynecologists are taking an interest in whether the law sets a dangerous precedent.

Originally enacted to protect children from meth labs, the law prohibits a “responsible person” from:

“exposing a child to an environment in which he or she…knowingly, recklessly or intentionally causes or permits a child to be exposed to, to ingest or inhale, or to have contact with a controlled substance, chemical substance or drug paraphernalia.”

But using the law to target pregnant women for drug use is criminalizing a health concern, an issue that was also argued this week before British legislators by comedian Russell Brand.

As Dr. Deborah Frank, a pediatrician and director of Boston Medical Center’s Grow Clinic for Children, said to the Times magazine, “to simplify a complex medical and psychological issue into a criminal issue is really just like using a hammer to play the piano.” The law could scare pregnant drug users away from getting treatment for their addiction and perhaps push them to have abortions, rather than receive severe legal punishment for their use.

Although the chemical-endangerment law seems unique to Alabama, the law would lend considerable support to the “fetal personhood” argument. Keith Mason, founder of Personhood USA, which seeks to establish a fetus’s right to live as equal to that of the mother’s, told the Times that personhood is the “rallying point” for the anti-abortion movement because it is the “crux of the issue.” Attempts to define fetuses as persons have failed in any state in which they have been introduced, but Mason believes the chemical-endangerment law, and laws like it, could get the anti-abortion movement where it wants to go.

But Emma Ketteringham, the director of legal advocacy at the National Advocates for Pregnant Women, said that applying the chemical-endangerment law to pregnant women violates constitutional guarantees of liberty, privacy, equality, due process and freedom from cruel and unusual punishment. “It starts with the use of an illegal drug, but what happens as a consequence of that precedent is that everything a women does whiles she’s pregnant becomes subject to state regulation,” she said, adding that the chemical-endangerment law is essentially a “personhood measure in disguise.”

“We can value the unborn as a matter of religion, ethics, or experience,” Lynn Paltrow, executive director of the National Advocates for Pregnant Women, told the Times. “But we can’t do that as a matter of law, and still value pregnant women.”